Mobile computing devices, such as smartphones and tablets, may require users to authenticate themselves to the device before allowing the user to perform various actions. For example, a smartphone lock screen may require the user to enter a PIN to unlock the smartphone, and may also require the user to enter passwords at various other points during usage of the smartphone. This may result in frequent interruption of the user's use of the mobile computing device, as the user has to stop whatever action they were attempting to authenticate themselves to the device. The user may also set security preferences so that the mobile computing device doesn't present certain prompts for authentication. For example, a smartphone's user may set preferences that prevent the smartphone from requesting a PIN to unlock the smartphone. This may streamline the user's experience, as the user may see fewer interruptions, but may make the mobile computing device less secure, as any other user could unlock and use the smartphone.
Certain signals from the mobile computing device may be used to more intelligently present authentication prompts to the user. For example, a PIN may be required to unlock a smartphone during certain times of day, but not during others. The mobile computing device may make decisions on when to require the user to authenticate based on detected usage patterns for the user. These decisions may be opaque to the user, who may not be aware of why their mobile computing device requires authentication in certain situations but not in others, and may be unable adjust the decisions made by the smartphone.